IP Law Daily, PATENT—Fed. Cir.: Network security patent claims held unpatentable in dispute between cybersecurity companies, (Apr 6, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

PTAB correctly found anticipation based on proper claim construction and a publicly accessible prior art reference.

In a non-precedential disposition, the U.S. Court of Appeals for the Federal Circuit affirmed the Patent Trial and Appeal Board’s (PTAB) decision holding claims of a network security decryption patent as unpatentable, concluding that substantial evidence supported the Board’s finding that a prior art reference anticipated the claims. The court rejected challenges to claim construction and to the status of the reference as a printed publication, determining that the Board correctly construed key claim language and reasonably found the reference publicly accessible before the patent’s priority date (Centripetal Networks, LLC v. Keysight Technologies, Inc., No. 24-2246 (Fed. Cir. Apr. 2, 2026)).

Background. The appellant, Centripetal Networks, LLC, develops network security solutions, including technologies for inspecting and managing encrypted data traffic. The appellee, Keysight Technologies, Inc., provides network testing and monitoring tools and had challenged Centripetal’s patent through inter partes review proceedings before the Board.

The asserted patent, U.S. Patent No. 10,284,526 (“’526 patent”), relates to methods and systems for network security using selective decryption of data packets. The invention describes decrypting packets in an encrypted communication flow, inspecting their contents, performing a “corresponding action” based on that inspection, and then re-encrypting and transmitting the packets to their destination.

The dispute arose when Keysight filed a petition for inter partes review challenging all claims of the ’526 patent on multiple grounds, including anticipation and obviousness. The Board instituted review and ultimately held all claims unpatentable on four alternative grounds, including anticipation by the Cisco IronPort AsyncOS User Guide (“IPUG”). Centripetal appealed, contesting both the Board’s claim construction and its determination that IPUG qualified as prior art.

Claim construction. The Federal Circuit first addressed the construction of the term “corresponding action” in claim 1. Citing Acceleration Bay, LLC v. Activision Blizzard, Inc., 908 F.3d 765 (Fed. Cir. 2018), the court reiterated that claim construction is reviewed de novo, with factual findings reviewed for substantial evidence. The court agreed with the Board that the term encompassed any action taken on a packet, including merely allowing the packet to proceed. It found no support in the claim language or specification for limiting the term to more restrictive actions.

The court rejected Centripetal’s argument that such a construction rendered other claim steps superfluous. Instead, it held that the “corresponding action” step and the later “transmitting” step were distinct in scope and sequence, thereby preserving the claim's structural integrity.

Anticipation. Turning to the anticipation issue, the court applied the substantial evidence standard, citing In re Chudik, 851 F.3d 1365 (Fed. Cir. 2017). It upheld the Board’s finding that IPUG disclosed each limitation of claim 1, including performing a “corresponding action” such as allowing, blocking, or redirecting traffic, followed by re-encryption and transmission. The court found that the record adequately demonstrated that IPUG taught both the action step and the subsequent transmission step as separate operations.

Because the court affirmed anticipation based on IPUG, it declined to address the Board’s alternative obviousness grounds, treating them as moot.

Printed publication status. The court next considered whether IPUG qualified as a “printed publication” under 35 U.S.C. § 102. Citing Jazz Pharmaceuticals, Inc. v. Amneal Pharmaceuticals, Inc., 895 F.3d 1347 (Fed. Cir. 2018), it reiterated that public accessibility is the key inquiry. The court held that substantial evidence supported the Board’s conclusion that IPUG was publicly accessible before the patent’s priority date. The record included an archived version of the webpage hosting IPUG, dated before the priority date, as well as expert testimony indicating that a person of ordinary skill in the art would have searched for and located such technical documentation. The court found this evidence sufficient to establish that IPUG was available to the interested public.

Conclusion. Having rejected Centripetal’s challenges to both claim construction and prior art status, the Federal Circuit affirmed the Board’s final written decision in full. The ruling left intact the determination that all claims of the ’526 patent were unpatentable.

The Case is No. 24-2246.

Judge: Lourie, A.

Attorneys: Daniel Noah Lerman (Herbert Smith Freehills Kramer (US) LLP) for Centripetal Networks, LLC. Gerard M. Donovan (Reed Smith LLP) for Keysight Technologies, Inc.

Companies: Centripetal Networks, LLC; Keysight Technologies, Inc.

Cases: Patent TechnologyInternet FedCirNews